Environment-based configuration in Flask - Mini Project: Build & Apply

Environment-based configuration

📖 Scenario: You are building a simple Flask web application that needs to behave differently depending on the environment it runs in, such as development or production. This is common in real projects where you want to enable debugging in development but disable it in production for security.

🎯 Goal: Create a Flask app that reads its configuration from an environment variable called FLASK_ENV. The app should set debug mode to true if FLASK_ENV is development, and false otherwise.

📋 What You'll Learn

Create a Flask app instance named app

Read the environment variable FLASK_ENV to determine the environment

Set app.config['DEBUG'] to true if FLASK_ENV is development

Set app.config['DEBUG'] to false if FLASK_ENV is not development

Add a simple route / that returns 'Hello, Flask!'

💡 Why This Matters

🌍 Real World

Many web applications need to behave differently in development and production environments. Using environment variables to control configuration is a common and secure way to manage this.

💼 Career

Understanding environment-based configuration is essential for deploying Flask apps safely and effectively in real-world jobs.

1

Create the Flask app instance

Import Flask from flask and create a Flask app instance called app.

Flask

from flask import Flask

# Create the Flask app instance called app
# Your code here

Need a hint?

Use Flask(__name__) to create the app instance.

2

Read the environment variable FLASK_ENV

Import os and create a variable called env that reads the environment variable FLASK_ENV using os.getenv.

Flask

from flask import Flask
import os

app = Flask(__name__)

# Read the environment variable FLASK_ENV into variable env
# Your code here

Need a hint?

Use os.getenv('FLASK_ENV') to get the environment variable.

3

Set app.config['DEBUG'] based on environment

Use an if statement to set app.config['DEBUG'] = True if env == 'development', otherwise set app.config['DEBUG'] = False.

Flask

from flask import Flask
import os

app = Flask(__name__)

env = os.getenv('FLASK_ENV')

# Set app.config['DEBUG'] to True if env is 'development', else False
# Your code here

Need a hint?

Use a simple if and else to set the debug config.

4

Add a route that returns a greeting

Add a route to app for the path '/' using @app.route('/'). Define a function called home that returns the string 'Hello, Flask!'.

Flask

from flask import Flask
import os

app = Flask(__name__)

env = os.getenv('FLASK_ENV')

if env == 'development':
    app.config['DEBUG'] = True
else:
    app.config['DEBUG'] = False

# Add a route '/' that returns 'Hello, Flask!'
# Your code here

Need a hint?

Use @app.route('/') decorator and define a function that returns the greeting.